# std::get(std::tuple)

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< cpp‎ | utility‎ | tuple

Defined in header `<tuple>` |  |
template< std::size_t I, class... Types > typename std::tuple_element<I, std::tuple<Types...>>::type& get( std::tuple<Types...>& t ) noexcept; | (1) | (since C++11) (constexpr since C++14)
template< std::size_t I, class... Types > typename std::tuple_element<I, std::tuple<Types...>>::type&& get( std::tuple<Types...>&& t ) noexcept; | (2) | (since C++11) (constexpr since C++14)
template< std::size_t I, class... Types > const typename std::tuple_element<I, std::tuple<Types...>>::type& get( const std::tuple<Types...>& t ) noexcept; | (3) | (since C++11) (constexpr since C++14)
template< std::size_t I, class... Types > const typename std::tuple_element<I, std::tuple<Types...>>::type&& get( const std::tuple<Types...>&& t ) noexcept; | (4) | (since C++11) (constexpr since C++14)
template< class T, class... Types > constexpr T& get( std::tuple<Types...>& t ) noexcept; | (5) | (since C++14)
template< class T, class... Types > constexpr T&& get( std::tuple<Types...>&& t ) noexcept; | (6) | (since C++14)
template< class T, class... Types > constexpr const T& get( const std::tuple<Types...>& t ) noexcept; | (7) | (since C++14)
template< class T, class... Types > constexpr const T&& get( const std::tuple<Types...>&& t ) noexcept; | (8) | (since C++14)

1-4) Extracts the Ith element from the tuple. I must be an integer value in `[`​0​`,` sizeof...(Types)`)`.
5-8) Extracts the element of the tuple t whose type is `T`. Fails to compile unless the tuple has exactly one element of that type.

### Parameters

t | - | tuple whose contents to extract

### Return value

A reference to the selected element of t.

### Notes

Feature-test macro | Value | Std | Feature
--- | --- | --- | ---
`__cpp_lib_tuples_by_type` | `201304L` | (C++14) | Addressing tuples by type (5-8)

### Example

Run this code

    #include <cassert>
    #include <iostream>
    #include <string>
    #include <tuple>

    int main()
    {
        auto x = std::make_tuple(1, "Foo", 3.14);

        // Index-based access
        std::cout << "( " << std::get<0>(x)
                  << ", " << std::get<1>(x)
                  << ", " << std::get<2>(x)
                  << " )\n";

        // Type-based access (since C++14)
        std::cout << "( " << std::get<int>(x)
                  << ", " << std::get<const char*>(x)
                  << ", " << std::get<double>(x)
                  << " )\n";

        const std::tuple<int, const int, double, double> y(1, 2, 6.9, 9.6);
        const int& i1 = std::get<int>(y); // OK: not ambiguous
        assert(i1 == 1);
        const int& i2 = std::get<const int>(y); // OK: not ambiguous
        assert(i2 == 2);
        // const double& d = std::get<double>(y); // Error: ill-formed (ambiguous)

        // Note: std::tie and structured binding can be
        // used to unpack a tuple into individual objects.
    }

Output:

    ( 1, Foo, 3.14 )
    ( 1, Foo, 3.14 )

### Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
LWG 2485 | C++11 (by index) C++14 (by type) | there are no overloads for const tuple&& | added these overloads ((4) and (8))

### See also

get(std::array) (C++11) | accesses an element of an `array` (function template)
get(std::pair) (C++11) | accesses an element of a `pair` (function template)
get(std::variant) (C++17) | reads the value of the variant given the index or the type (if the type is unique), throws on error (function template)
get(std::ranges::subrange) (C++20) | obtains iterator or sentinel from a std::ranges::subrange (function template)
get(std::complex) (C++26) | obtains a reference to real or imaginary part from a std::complex (function template)
tie (C++11) | creates a tuple of lvalue references or unpacks a tuple into individual objects (function template)
Structured binding (C++17) | binds the specified names to sub-objects or tuple elements of the initializer

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